1. Field of the Invention
The present invention relates to an active geometry control suspension system of a vehicle, and more particularly, to an active geometry control suspension system that can minimize load applied to an actuator by minimizing offset of a load input portion and a load output portion of the actuator.
2. Description of Related Art
In general, a suspension system of a vehicle is a device that prevents damage to the vehicle body or freight and improves ride comfort by connecting the vehicle shaft with the vehicle body such that vibration or shock applied from the road surface to the vehicle shaft is not directly transmitted to the vehicle body while the vehicle travels.
The suspension system includes a chassis spring that alleviates shock from the road surface, a shock absorber that improves ride comfort by attenuating free oscillation of the chassis spring, and a stabilizer bar that suppresses rolling of a vehicle.
Both sides of a straight portion of the stabilizer bar are fixed to the vehicle body and both ends are fixed to a lower arm or a strut bar through a stabilizer link.
Accordingly, the stabilizer bar does not operate when the left and right wheels simultaneously move up/down, but is distorted when the left and right wheels move up/down relative to each other, thereby performing an anti-roll function that suppresses roll of the vehicle, using an elastic distortion force.
That is, the stabilizer bar is distorted and stabilizes the position of a vehicle body by using the elastic distortion force, when the vehicle turns and the outer side of the vehicle body while turning becomes inclined due to centrifugal force, or a relative phase difference is generated between the left and right wheels due to a bump or a rebound while the vehicle travels.
However, the stabilizer bar does not sufficiently ensure stability in turning under various conditions by using only the elastic distortion force thereof because the rigidity value is constant. Therefore, an active roll control unit that can perform active roll control by connecting an actuator implemented by a hydraulic cylinder, a motor, or the like to the front end of the stabilizer bar has recently been developed and applied.
The active roll control unit has a mechanism that changes the connection length between a lower arm and one end of a stabilizer bar and changes distortion rigidity of the stabilizer bar by changing the position of a connection point with an actuator, which is implemented by a hydraulic cylinder or a motor, at a connecting portion of a stabilizer link connecting the lower arm with one end of the stabilizer bar.
Further, members are connected to the connecting portion by a ball joint, such that a rotation degree of freedom within a predetermined range.
FIG. 1 is a partially cut-away perspective view of an active roll control unit according to a first exemplary embodiment of the related art.
Referring to FIG. 1, an active roll control unit according to the first exemplary embodiment of the related art includes an actuator 100, a screw shaft 102, a screw slider 104, a ball joint 106, and a stabilizer link 108.
The actuator 100 is a motor and disposed under a lower ram 110 and the screw slider 104 supported by a guide rail 112 fixed to the lower arm 110 fits on the screw shaft 102, which is a rotary shaft of the actuator 100.
The ball joint 106 is formed above the screw slider 104 and connected with the lower end of the stabilizer link 108.
Therefore, when the actuator 100 operates, the screw slider 104 moves the lower end of the stabilizer link 108 while moving left or right in accordance with the rotational direction of the screw shaft 102, such that the connection length between one end of the stabilizer bar and the lower arm 110 changes.
However, in the configuration described above, offset (OS) is generated between the screw shaft 102 and the ball joint 106, such that a moment is generated and operation load applied to the actuator 100 increases.
FIG. 2 is a partially cut-away perspective view of an active roll control unit according to a second exemplary embodiment of the related art.
Referring to FIG. 2, an active roll control unit according to the second exemplary embodiment of the related art includes sliders 120, a ball joint 122, a stabilizer link 124, and an actuator 126.
The sliders 120 fit on guide rails 130 disposed longitudinally under a lower arm 128, to be movable left and right.
The ball joint 122 is integrally formed with the sliders 120 and connected with the lower end of the stabilizer link 124.
The actuator 126 is disposed behind the stabilizer link 124 and the screw shaft 132 that is a rotary shaft is fastened to a pushrod 134 connected to the lower portion from the middle portion of the stabilizer link 124.
Accordingly, when the actuator 126 operates, the pushrod 134 pushes or pulls the stabilizer link 124 while moving in accordance with the rotational direction of the screw shaft 132, thereby changing the connection length between the lower arm 128 and one end of the stabilizer bar.
In the configuration described above, however, although it is possible absorb oscillation in three directions while mounting the actuator 106 on the vehicle body, as offset (OS) is generated between the portion of the pushrod 134 and the sliding portion, a moment is generated and operation load applied to the actuator 126 increases.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.